textproduct: Quad Cities

KEY MESSAGES

- Rounds of nocturnal and diurnal convection through Monday night will bring a risk of locally heavy rainfall due to weak winds aloft. If the heavy rain is persistent more than 1 hour, flash flooding is possible.

- Heat and humidity will return around mid-week with temperatures in the 90s and heat indices pushing 100 or higher. The probability of heat headlines around mid-week is 33-40 percent.

UPDATE

Issued at 943 PM CDT Sun Jun 7 2026

The flood watch has been expanded into southeast Iowa, far northeast Missouri and a small part of west central Illinois.

Very high atmospheric moisture levels (00z DVN PWAT was over 95% percentile) will remain across the area tonight. Very short term models shows Corfidi vectors opposing themselves for much of the overnight hours with speeds around 5 knots. This indicates very slow storm movement and the potential for storms to repeat over the same areas. 18z REFS LPMM shows large 2+ inch areas of rainfall occurring across southeast Iowa overnight with the potential for 3+ inches.

Additionally, warm rain processes should dominate which will allow high rainfall rates, potentially 2-3 inches per hours.

SHORT TERM /THROUGH TUESDAY/

Issued at 208 PM CDT Sun Jun 7 2026

Our area has been the focal point of weak synoptic lift from the approaching upper low, exceptionally high PWAT air mass around 2 inches, and a mesoscale boundary from Lake Michigan which is all creating a nearly continuous convective activity over the I-80 and and north this morning. Day time temperatures and east winds under these storms have held the boundary in place, while predominantly dry conditions south have allowed for heating. This will set the stage for additional torrential rain producing storms over the area, especially the northeast 1/2. Given this scenario, I've opted to issue a Flood Watch for this scenario where repeated torrential rain is expected on and off through Monday.

Models are not handling this well, but with the upper low lifting up over the area, this focusing mechanism is unlikely to stop until the upper low's passage. We have had seen flash flooding already take place in Bureau County in our east, and additional flooding appears likely, despite starting the day with dry soil conditions in many areas. Several reports through Noon are 2 to 5 inches of rain this morning.

Rainfall tonight in general may average 0.5 to 1.0 inches, but in areas that see the repeated storms, tonight may see more areas of 2 to 5 inches. That certainly won't be everywhere, but in the northeast 1/2 were especially prone to this, with advection over the boundary.

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/

Issued at 207 AM CDT Sun Jun 7 2026

Tuesday through Sunday Assessment...high (>80%) confidence of temperatures well above normal. Low (20-25%) confidence for rain.

Trends with the models continue to show temperatures well above normal for much of the week.

However, the highest heat indices now look to occur in the Tuesday/Wednesday time frame. A seasonably strong front arriving Wednesday night will bring cooler temperatures on Thursday with temperatures moving to near normal for next weekend.

Heat indices Tuesday continue to indicate 95 to 100 but areas south of I-80 have a 30-40% probability of exceeding 100. On Wednesday the probability of seeing heat indices of 100+ is now at 50-60%. Depending upon how rain chances play out, heat headlines may be needed in the Tuesday/Wednesday time frame.

The model consensus indicates the daylight hours of Tuesday are dry. Tuesday night into Wednesday is a question. A weak signal has started to develop suggesting a nocturnal storm complex running around the edge of the heat dome. If this occurs it would play significantly into the need for potential heat headlines Wednesday.

Albeit a weak signal, some of the ensemble members of the various models are pointing to rain and have a 20-30 percent chance for rain Tuesday night into Wednesday.

Wednesday night into Thursday looks interesting.

A much stronger front is progged to move through the area that will be associated with a strong upper level disturbance. Winds in the mid-levels of the atmosphere are progged to be around 50 knots indicating organized storms with the potential for severe storms. CSU ML progs and other ML analog sites from the June 6th model runs have a 15-30% probability of severe storms occurring. Thus the transition from hot and humid conditions may have severe storms.

Thus Wednesday night has the best chances for rain. The current model consensus has 50-70 percent chances for rain. Outside of Wednesday night, the model consensus has daily 20-35 percent chances for rain Thursday through Sunday.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1223 AM CDT Mon Jun 8 2026

Nocturnal convection is now developing due to a combination of the LLJ and convectively induced disturbance. Areal coverage will slowly increase through 12z/08, especially along/west of the Mississippi. Boundaries from said convection will be the foci for diurnal convection any time after 15z/08. A front moving into eastern Iowa after 18z/08 will slowly bring the rain to an end by or shortly after 00z/09. Light winds after 00z/09 raises the possibility of fog that will need to be reviewed for the 12z/09 TAFs.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Flood Watch through this evening for IAZ040>042-051>054- 063>068-076>078-087>089-098-099. IL...Flood Watch through this evening for ILZ001-007-009-015>018- 024-025-034. MO...Flood Watch through this evening for MOZ009-010.